Different elements have different charges depending on whether it is a metal or non - metal.

Metals form POSITIVE ions - by loosing electrons

Non - metals form NEGATIVE ions - by gaining electrons

REMEMBER:When a metal and non - metal react, their aim is to get a full outer shell, the only way to do this is to 'steal' from eachother. A metal has too many electrons, (so it's positive) therefore it gets rid of the ones in its outer shell and the non - metal takes them, because it has too little. Hence, both atoms will now have a full outer shell.

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Questions

1. Why do ionic compounds have high melting and boiling points?

2. When are ions formed?

3. Do metals form positive or negative ions? - Why?

4. Do non - metals loose or gain electrons? - Why?

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Ionic Bonding: The Charge of an Ion

How to work out the charge of an ion:

For metals, the charge is equal to the number of electrons in its outer shell (or its group number) e.g...

Sodium = Na+

Magnesium = Mg2+

Aluminium = Al3+

For non - metals, the charge is equal to the number of electrons it needs to get a full outer shell (or the group number minus eight) e.g...

Nitrogen = N3-

Oxygen = O2-

Chlorine = Cl-

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Questions

1. If sodium reacted with chlorine, which element would loose an electron and why?

2. Draw this reaction using electronic structure.

3. The electronic configuration of element X is 2.8.5. What is it's ionic charge?